System for inside powder striping of welded food cans

ABSTRACT

A powder stripe application system wherein substantially all powder introduced into the system is applied to side seam areas of can bodies with that powder which is not initially bonded to a can body being directly recycled within the system. The system includes a delivery nozzle which has an adjustable mounting which permits the powder stream to be positioned as desired.

This invention relates in general to new and useful improvements in thecoating of can bodies, and more particularly to the inside powderstriping of welded food cans.

The powder striping of the side seam area of welded food cans possessesa problem different from the powder striping of welded beverage cans inthat the welded beverage cans, after they have been side striped, areprovided with an over-coat which is baked in place with the result thatany stray powder particles not applied to the side seam area are fullybonded to the interior of the can body and cannot become loose at alater date and thus form a contaminant. On the other hand, the over-coatis not required with respect to food cans, and it would not beeconomically feasible to provide such an over-coat merely for thepurpose of assuring the bonding of stray powder particles to theinterior of a food can so that it cannot later become a contaminant.

In the formation of a welded food can, no internal coating is appliedalong the two edges of the body blank which are to be welded togetherwith the result that the side seam area of a welded food can has nointernal coating. When the can body is formed of steel that is tin free(no tin coating), it is necessary to apply a coating to the interior ofthe can body both to prevent corrosion of the can body and thecontamination of the food product by way of transferred metal ions.Accordingly, after the side seam has been formed it is necessary to coatthe side seam area, and this may be beneficially accomplished by theelectrostatic depositing of coating material in powder form. The powderso applied is heated by the inherent temperature of the side seam areadue to the welding, and automatic bonding of the powder occurs in theside seam area.

It has been found that when powder application systems suitable for usein coating side seams of beverage cans have been utilized, there havebeen certain deficiencies particularly by way of stray powder particles.The powder particles which stray from the side seam area frequently areheated to the extent that they loosely bond to the previously appliedcoating, but during handling of the can come loose and thus exist withinthe food product as a contaminant. In accordance with this invention, itis highly desirable that the stray powder particles not become bonded toportions of the can body adjacent the side seam area, and this can beeffected only by eliminating the stray powder particles from the areaoutside of the side seam area.

In accordance with this invention, there is provided a suitable systemwhich not only provides means for catching the powder particles which donot adhere to the side seam area, but also to retrieve all powder whichis dispensed between adjacent can bodies.

It is also a primary feature of this invention to provide a powdersystem wherein the powder which is directed against a can body side seamportion and does not bond thereto is immediately retrieved andrecirculated directly within the system. Thus substantially all powderentering the system is applied to can bodies.

Another feature of the invention is the construction of a powderapplicator wherein the delivery nozzle may be readily adjusted asrequired to assure the directing of powder against the side seam area ofcan bodies to be coated.

With the above and other objects in view that will hereinafter appear,the nature of the invention will be more clearly understood by referenceto the following detailed description, the appended claims, and theseveral views illustrated in the accompanying drawings.

IN THE DRAWINGS

FIG. 1 is a schematic view showing the overall system of the powderstripe applicator of this invention.

FIG. 2 is a schematic top plan view of the powder applicator, showingthe several adjusted positions of the delivery nozzle.

FIG. 3 is a longitudinal sectional view taken through the applicatorgenerally along the line 3--3 of FIG. 2, and shows the constructionaldetails of the mounting of the delivery nozzle.

FIG. 4 is a transverse sectional view taken generally along the line4--4 of FIG. 3, and shows the adjustable mounting of the nozzle housingon a supply fitting.

FIG. 5 is a transverse sectional view taken generally along the line5--5 of FIG. 3, and shows the adjustable mounting of the delivery nozzlewith respect to the housing.

Reference is first made to FIG. 1 wherein the powder stripe applicationsystem of this invention is best illustrated and is identified by thenumeral 10. First of all, the system 10 includes a dispenser 12 whichdelivers to a delivery tube 14 an air entrained supply of powder. Thedelivery tube extends through the customary welding horn 16 and hornextension 18 to an applicator 20 which in itself is not part of thisinvention. The applicator 20, however, will be provided with suitablemeans (not shown) for defining a sealed area of which one wall will bedefined by a side seam area of a can body being striped. A suitabledelivery nozzle, to be described in detail, delivers the powder into theconfined area and generally directs the powder against the side seamarea as is schematically illustrated in FIG. 1. The can body is onlypartially shown and is identified by the numeral 22. .Iadd.As is wellknown to those skilled in the art, a series of can bodies 22, 22a, and22b are formed about a conventional welding horn 16, welded, andconveyed in a linear path in spaced end-to-end relationship from thehorn to applicator 20. The cans are moved sequentially over theapplicator which is disposed inside of the can bodies and is surroundedby them as shown diagrammatically in FIG. 1. .Iaddend.

A large portion of the delivered powder becomes electrostatically bondedto the side seam area and is then fused in situ by the inherent heatresulting from the formation of the side seam being welded. Others ofthe powder particles bounce off the side seam area and enter into anupper part of a catcher 24. Certain powder particles flowing directlythrough the applicator 20 enter the upstream side of the catcher 24 asis diagrammatically illustrated.

The catcher 24 in itself is also not part of this invention and normallywill be supported from the applicator 20. .Iadd.As showndiagrammatically in FIG. 1, catcher 24 is disposed within can bodies 22and is surrounded by each of the can bodies 22, 22a, and 22b in sequenceas they move over the catcher. The catcher 24 is located downstream ofthe applicator 20 with respect to the path of movement of the can bodies22, 22a, and 22b. .Iaddend.The catcher 24 is provided with a return tube26 which extends through the horn 16 and horn extension 18 externally ofthe welding apparatus.

It is to be understood that the can bodies will be delivered to theapplicator in slightly spaced relation so that between each can bodythere will be a spray of powder particles which tend to exit thesystem,. These powder particles, however, are caught by a scavenger 28which is positioned adjacent the applicator 20 .Iadd.outside of the pathof the can bodies (see FIG. 1). .Iaddend.and which is provided with areturn line 30. The system 10 includes a recovery unit 32 which may bein the form of an integral cyclone/bag house which collects new,returned and scavenged powder and initiates powder conditioningincluding drying and mixing. The constructional details of the recoveryunit 32 may vary.

It will be seen that the recovery unit 32 receives new powder, asrequired, from a new powder supply 34. The new powder is pneumaticallydelivered into the system.

The return line 30 also opens into the recovery unit and returns thepowder particles which escape between adjacent can bodies. This returnis also of a pneumatic delivery type.

The return tube 26 has a suction formed therein generally by way of avacuum flow transducer which forms a major component of the return unitwhich is generally identified by the numeral 36. The return unitrequires air under pressure to operate the same.

It is to be understood that the catcher 24 will receive not onlynon-applied powder, but also any poorly adhered powder which falls offjust after deposition. This return powder may include particles whichare heat bonded together, and therefore the return may be considered toinclude oversize and agglomerated particles.

Plant air is directed by means of a suitable unit 38 both onto thedispenser 12 under pressure and into an air dryer 40 which removes oil,water and particulate contamination from air used to condition, meter,deliver and return powder. Part of the conditioned air is directed intothe vacuum flow transducer of the return unit 36 while other is directedinto the dispenser 12.

The powder particles collected by the catcher 24 and the scavenger 28are mixed with the new powder from the new powder supply 34 in therecovery unit 32 and are pneumatically directed to a sieve 42 whichseparates the oversize and agglomerated particles and discharges theminto an oversize collector 44. The remaining particles are directed intothe dispenser for delivery to the applicator.

It is to be understood that the applicator has associated therewith aD.C. power supply which will be connected to corona charging needles(not shown), and that the can bodies being side striped will be groundedso that the charged powder particles will be directed toward and adheredto the side seam area.

In order that the power particles may be properly directed to the sideseam area of a can body and at the desired angle to the can body, thereare provided in the applicator means for adjustably mounting a deliverynozzle 50. First of all, it is to be understood that the applicator willinclude a supply fitting 52 which, in turn, is carried by and suitablycoupled to the delivery tube 14. The mounting means mounting thedelivery nozzle 50 for adjustment relative to the supply fitting 52 inpart includes a housing generally identified by the numeral 54. Thehousing 54 is of a two-piece construction and includes a first housinghalf 56 associated with the supply fitting 52 and a second housing half58 associated with the delivery nozzle 50.

The housing half 56 is formed to include an outer wall 60 and an innerwall 62 joined by a peripheral portion 64. The outer wall 60 has anaxial opening 66 therethrough while the inner wall 62 has a furtheraxial opening 68 therethrough which is aligned with but is of a smallersize than the opening 66.

Between the two walls 60, 62 the housing half 56 defines a socket 70 inwhich there is received a mounting flange 72 of the supply fitting 52.The supply fitting 52 is also provided with a closure flange 74 which isspaced from the flange 72 and with the exterior of the supply fitting 52being undercut as at 76 in alignment with the outer wall 60. The supplyfitting 52 is provided with a through bore 78 having a flared inner endportion 80.

If desired, the supply fitting may be telescoped over the free end ofthe delivery tube 14 and secured in place thereon by means of a setscrew threaded into a radial bore 82.

It will be seen that the flange 72 is snugly received between the sidewalls 60 and 62 and generally forms a seal therewith. On the other hand,the flange, together with the remainder of the supply fitting 52, isradially adjustable within the socket 70 and the housing half 56 by twopairs of adjusting screws 84 and 86, as is best shown in FIG. 4.Preferably the periphery of the flange 72 has flats 88 thereon forengagement between adjusting screws 86. Thus when the supply fitting 52has its axis horizontally disposed, the housing 54 together with thedelivery tube 50 may be selectively adjusted both vertically andhorizontally.

The housing half 58 also includes an outer wall 90 and an inner wall 92which are connected together by a peripheral portion 94 and definetherein a socket 96. The outer wall 90 has an oversize opening 98therethrough loosely receiving the delivery tube 50.

The central portion of the inner wall 92 has a bore therethrough alignedwith the bore 68, the bore in the inner wall 92 being defined by aspherical seat 100. The inner end of the delivery nozzle 50 is providedwith a spherical surface 102 which engages the spherical seat 100 andprovides a seal between the delivery nozzle 50 and the housing 54 whileat the same time permitting the adjustment of the delivery nozzle 50relative to the housing 54 for angular pitch and yaw. In order to adjustthe angular pitch and yaw, the inner end portion of the delivery nozzle50 is provided with a flange 104 which is positioned within the socket96. The flange 104 has a series of radial recesses 106 in an outermostface thereof with these recesses having engaged therein inner ends ofadjusting screws 108 which are arranged in two sets.

Finally, the housing halves 56, 58 are secured together by a pluralityof axially extending fasteners 110 which permit the halves 56, 58 to berotatably adjusted relative to one another. Thus the housing 54 and thedelivery nozzle 50 may be adjusted about a horizontal axis in arotational manner.

Although only a preferred embodiment of the invention has beenspecifically illustrated and described herein, it is to be understoodthat minor variations may be made in the powder stripe applicationsystem and the mounting of the delivery nozzle without departing fromthe spirit and scope of the invention as defined by the appended claims.

What is claimed as new is:
 1. A continuous closed loop powder stripeapplication system for electrostatically applying powder to membersmoving along a predetermined path in spaced relation, said systemcomprising an applicator, a catcher for receiving excess powder, ascavenger for receiving powder dispensed between members, a recoveryunit for receiving powder from said scavenger and said catcher, a returnsystem between said catcher and said recovery unit, means connectingsaid scavenger to said recovery unit, a new powder supply connected tosaid system in accordance with powder utilization, a dispenser forreceiving powder from said recovery unit, and a delivery tube fordelivering powder to said applicator.
 2. A system according to claim 1wherein there are means in advance of said dispenser for removingoversize powder particles from said system.
 3. A system according toclaim 2 wherein said means for removing oversize particles is disposedbetween said recovery unit and said dispenser.
 4. A system according toclaim 2 wherein said means for removing oversize particles is disposedbetween said recovery unit and said dispenser and includes a sieve.
 5. Asystem according to claim 1 wherein said return unit includes suctionmeans actuated by air under pressure and said dispenser has an airsupply for effecting the delivery of powder to said applicator under airentrained conditions.
 6. A system according to claim 1 wherein saidapplicator includes a generally horizontally extending delivery nozzleand means mounting said delivery nozzle for vertical and horizontaltranslation.
 7. A system according to claim 1 wherein said applicatorincludes a generally horizontally extending delivery nozzle and meansmounting said delivery nozzle for vertical and horizontal translationand for angular pitch and yaw.
 8. A system according to claim 1 whereinsaid applicator includes a generally horizontally extending deliverynozzle and means mounting said delivery nozzle for vertical andhorizontal translation and for rotation about a horizontal axis.
 9. Asystem according to claim 1 wherein said applicator includes a generallyhorizontally extending delivery nozzle and means mounting said deliverynozzle for vertical and horizontal translation, for angular pitch andyaw, and for rotation about a horizontal axis.
 10. A system according toclaim 1 wherein said applicator includes a generally horizontallyextending delivery nozzle and means for mounting said delivery nozzlefor angular pitch and yaw.
 11. A system according to claim 1 whereinsaid applicator includes a generally horizontally extending deliverynozzle and means for mounting said delivery nozzle for angular pitch andyaw and for rotation about a horizontal axis.
 12. A system according toclaim 1 wherein said applicator includes a generally horizontallyextending delivery nozzle and means mounting said delivery nozzle forrotation about a horizontal axis.
 13. A powder applicator comprising asupply fitting, a separately formed delivery nozzle and means mountingsaid delivery nozzle for vertical and horizontal translation relative tosaid supply fitting when said supply fitting is horizontally disposed.14. The powder applicator of claim 13 wherein said mounting meansinclude means mounting said delivery nozzle for angular pitch and yaw.15. The powder applicator of claim 13 wherein said mounting meansinclude means mounting said delivery nozzle for angular pitch and yawand for rotation about a horizontal axis.
 16. The powder applicator ofclaim 13 wherein said mounting means includes a housing formed of twohalves. one of said housing halves defining a socket, said supplyfitting having a flange seated in said socket for radial movement, andsets of adjusting elements for engaging said flange adjusting saidhousing and said delivery nozzle vertically and horizontally relative tosaid supply fitting.
 17. The powder applicator of claim 14 wherein saidmounting means includes a housing formed of two halves, one of saidhousing halves defining a socket, said socket including a sphericalseat, said delivery nozzle having a spherical end portion engaging saidseat, a positioning flange carried by said delivery nozzle disposedwithin said socket, and axial sets of adjusting elements engaging saidpositioning flange and adjusting said angular pitch and yaw.
 18. Thepowder applicator of claim 17 wherein the other of said housing halvesdefines a second socket, said supply fitting has a second flange seatedin said second socket for radial movement, and sets of adjustingelements for engaging said second flange and adjusting said housing anddelivery nozzle vertically and horizontally relative to said supplyfitting.
 19. The powder dispenser of claim 18 wherein said housinghalves have a common axis, and means for joining together said housinghalves in selected rotated positions relative to said common axis..Iadd.
 20. A continuous closed loop powder stripe application system forelectrostatically applying powder to inner surfaces of can bodies movingalong a predetermined linear path in spaced end to end relation, saidsystem comprising:an applicator for applying a stripe of powder to aninner surface of each can body; a catcher for receiving excess powder,said catcher being disposed adjacent to said applicator downstream ofsaid applicator along said linear path of movement of can bodies, saidapplicator and said catcher being positioned for being successivelysurrounded by can bodies moving along said linear path; a scavenger forreceiving powder dispensed between can bodies, said scavenger beingdisposed outside of said linear path of can bodies; a recovery unit forreceiving powder from said scavenger and said catcher; a return systembetween said catcher and said recovery unit to transport powder fromsaid catcher to said recovery unit; means connecting said scavenger tosaid recovery unit to permit powder collected in said scavenger to flowto said recovery unit; a new powder supply connected to said system inaccordance with powder utilization; a dispenser for receiving powderfrom said recovery unit; and a delivery tube for delivering powder fromsaid dispenser to said applicator..Iaddend. .Iadd.
 21. The system ofclaim 20 in which said catcher is supported from saidapplicator..Iaddend. .Iadd.22. The system of claim 20 in which saidcatcher includes an upper part having an opening adapted to receiveparticles not adhering to said inner can body surface and an upstreamopening adapted to receive particles flowing from saidapplicator..Iaddend. .Iadd.23. The system of claim 21 in which saidcatcher includes an upper part having an opening adapted to receiveparticles not adhering to said inner can body surface and an upstreamopening adapted to receive particles flowing from saidapplicator..Iaddend.